This project will: (1) Determine the construct validity of alternative indicators of functional status in individuals with, or at risk for, HIV-1 associated neurocognitive disorders. We have intentionally included functional status indicators that vary by source(patient, clinician), scope(overall rating, specific domain ratings), modality(time use, reported difficulty, need for help, observed performance on standardized tasks, and time reference(prior month, 24 hour- period). No clear consensus currently exists on the value of these alternative assessment techniques in HIV research, or whether they can be rationally combined. (2) Examined the criterion validity of the different measures, that is, the relationship between the function indicators and indicators of disease severity(viral load and neuropsychological status). The validity of self- report measures, for example, may vary with self-reports less accurate (relative to severity indicators among subjects with cognitive impairment or mood disorders. (3) Examine the relationship between particular domains of neuropsychological performance and specific domains of function. For example, among the mildly impaired, deficits in planning may be associated with impairment in higher-order functions (i.e., medication management). At this point, it is still unclear which domains of neuropsychological performance best predict onset of different kinds of functional deficit. In such analyses, it is important to examine non-cognitive sources of functional deficit as well, including fatigue, medical status, direct effects of viral load (association between viral load and functional status controlling for neuropsychological status), and mood disorders. To accomplish these goals, this proposal will assess predictors of functional status in the entire cohort (n=460), including a performance function test. It will also examine the 170 subjects at the Columbia University site in more detail, with enriches assessments of function(time budgets, unmet needs), neuropsychological status (executive function tests), and psychiatric status(SCID, apathy, fatigue). This work extends prior research conducted as part of the Dana Consortium on Therapy for HIV Dementia.